Adsorption of Lead (II) in Liquid-Solid Interfaces on Natural and Modified Hydroxyapatite

The removal of lead from aqueous solutions was studied using the liquid-solid extraction method. The solids used are the crude phosphocalcic hydroxapatite [Ca10(PO4)6(OH)2] (HAPc), and phosphocalcic hydroxapatite treated with 5 % lactic acid solution (HAPal). The extraction results showed the influence of the initial concentration of Pb (II) and temperature of the suspensions. The maximum adsorption capacities of each material (HAPc and HAPal) were obtained with the application of Langmuir adsorption model. The most important quantity was founded as 41,84mg/g for HAPal. Isotherms established at different temperatures showed that this parameter affects greatly the adsorption of Pb (II) on both adsorbents. The best results were obtained at room temperature (25°C) compared with those recorded at 50°C.Finally, the results of this study allow us to note that the hydroxiapatite material can be as good extractant solid, for heavy metals, especially when it is modified with lactic acid.